The tree with the red leaves had particularly impressive colors, but
only when viewed from about where the group is standing. From where I took
the photo above, the leaves look fairly bland, at least relatively
speaking. As you can tell from the shadows, the leaves were not being
backlit.... it was a hazy day and the sun was more or less to my back in
the photo above.

This little clearing was behind a building, so most people never see it
to begin with, but those who do generally arrive from behind the camera
position in the photo above. They see the view in the photo above, then
return back to the main area, missing most of what the tree has to offer. In this respect, we were lucky to have arrived via a back route...

The light in the clearing was a bit other-worldly to begin with, likely
due to a combination of the hazy day and the nature of the clearing, with
high trees most of the way around but open sky directly above.

This is the scene we found when we entered the clearing from behind.
(The first photo appearing above was taken from the path near the corner of
the building.)

As we moved through the clearing to the red leaves, they suddenly came
alive in a way digital photography can not capture. They seemed positively
luminescentb, as if they were somehow fluorescently turning non-visible
light into visible light. In the next photo, I had to tone the image down
unnaturally — as evidenced by the dark background —
just to keep all the red from blowing out the color
channels to white...

Despite darkening the whole photo quite a bit, the red channels are
still blown out so that the leaves have become solid blotches of whatever
the brightest red your monitor can display. At times like this the technical
limitations of digital photography makes me sad.

When I suggested to a group of folks that they'd get a more spectacular
view by moving to the back of the clearing, they were happy enough to try
but it was clear from their exuberant ooohs and aaaahs that they hadn't
really expected much change. They were suitably impressed.

I posted before about the benefits of a polarizing
filter for fall-foliage photography, and I know that in some cases the
human eye can also notice a difference due to light polarization, but I
don't think that's involved in this burning-red-leaf situation (because blocking
polarized light would make it appear darker in real life, allowing it to
appear more vibrant in photos due to the resulting change in camera exposure).

It'll be interesting to visit again next year to see whether it was something intrinsic
to the leaves or the area, or some kind of passing effect that just happened to occur that day.